1. Field of the Invention
The present invention relates generally to a high brightness and multiple beamlets X-ray source, more specifically to a high brightness and multiple beamlets X-ray source for patterned particle generation, and most specifically to a high brightness and multiple beamlets X-ray source for particle generation through a one-layer pattern generator. Alternatively, the invention may be scaled to generally relate for remote detection, more specifically to remote detection of explosives, and still more specifically to remote detection of certain chemical species.
2. Description of the Relevant Art
Photolithography Applications
As the dimensions of semiconductor devices are scaled down in order to achieve ever higher level of integration, optical lithography will no longer be sufficient for the needs of the semiconductor industry. Alternative “nanolithography” techniques will be required to realize minimum feature sizes of 0.1 μm or less. Therefore, efforts have been intensified worldwide in recent years to adapt established techniques such as X-ray lithography, extreme ultraviolet lithography (EUVL), and electron-beam (e-beam) lithography, as well as newer techniques such as ion projection lithography (IPL) and atomic-force-microscope (AFM) lithography, to the manufacture of 0.1 μm-generation complementary metal-oxide-semiconductor (CMOS) technology. Significant challenges exist today for each of these techniques: for X-ray, EUV, and projection ion-beam lithography, there are issues with complicated mask technology; for e-beam and AFM lithography, there are issues with low throughput.
Focused ion beam (FIB) patterning of films is a well-established technique (e.g. for mask repair), but throughput has historically been a prohibitive issue in its application to lithographic processes in semiconductor manufacturing. A scanning FIB system would have many advantages over alternative nanolithography technologies if it can be made practical for high volume production. Such a system could be used for maskless and direct (photoresist-less) patterning and doping of films in a semiconductor fabrication process. It would be necessary to focus the beam down to sub-μm spot sizes.
U.S. Pat. No. 7,084,407, filed Feb. 13, 2003, provides for a counter bored electrode capable of focusing an electron beam to small sizes, which is hereby incorporated by reference in its entirety.
U.S. Pat. No. 5,945,677 to Leung et al. issued Aug. 31, 1999 describes a compact FIB system using a multicusp ion source and electrostatic accelerator column to generate ion beams of various elements with final beam spot size down to 0.1 mm or less and current in the mA range for resist exposure, surface modification and doping.
Conventional FIB columns consist of multiple lenses to focus the ion beams. In order to get smaller feature size, small apertures have to be used to extract the beam and at the same time act as a mask. For the extraction of ions from a plasma source using a long, narrow channel, aberration is always a problem because of the edge effect.
Conventional multicusp plasma ion sources are illustrated by U.S. Pat. Nos. 4,793,961; 4,447,732; 5,198,677; 6,094,012, which are hereby incorporated by reference.
Additional remaining problems in the semiconductor field relate to the manufacture of masks, changing of masks, and registration of masks. A simpler technique would be to have an array of electron beamlets that can be controlled in such a manner so as to expose or block an ion or electron beam from a target wafer in production. Such array of electron beamlets could be stepped from device to device on the target wafer, or may be moved within a single device in precise positions.
Remote Detection Applications
Recent terrorist attacks have led to an elevated concern with regard to national and international security and have prompted security measures to be increased. These security measures, however, were not designed for scenarios in which individuals appear in an open environment and a security decision must be made at a distance from a suspected explosive. For scenarios such as these, standoff explosive detection is required; where physical separation puts individuals and vital assets outside of a zone of severe damage should an explosive device detonate. The difficulty of the standoff explosive detection task is exacerbated by several factors, including dynamic backgrounds that can interfere with the signal from the explosive, the potential for high false alarms, and the need to ascertain a threat quickly so that action can be taken [1]
Successful standoff explosives technology involves detection of a weak signal in a noisy environment. This background is also often dynamic, so that exemplary performance in controlled laboratory settings may be quite poor performance when applied in the field. The speed with which the detection is performed is a crucial factor when a potential threat is rapidly approaching. Finally, all explosives detection methods both generate alarms in the absence of threat, and do not alarm in the presence of a true threat. [1]
Standoff Compton backscatter X-ray detection system has been used to detect explosive, plastic weapons, and drugs. Using low-energy X-rays, the target is illuminated. Compton backscatter photons are collected that are subsequently emitted from the target. Photomultipliers detect light flashes in plastic that result from the backscatter photons. The image is assembled by scanning the X-ray over the target and detecting in synchronization the backscattered photons. Backscattered photons are produced relatively efficiently by substances of low atomic number. [1]
There is good potential for X-ray imaging at standoff distance of approximately 15 m. Research in the areas of high photon flux X-ray sources, pulsed X-ray sources, smaller focal spots for scanned beams, and focused X-ray beams can contribute to the successful development of standoff X-ray imagers. An alternative approach may be coded aperture imagers since they are able to achieve high sensitivities with practical devices.